1. Field of the Invention
The present invention relates to a rigid raft formed of rigid composite material, and having an electrical system and/or a fluid system embedded therein, and particularly, but not exclusively, to a gas turbine engine rigid raft.
2. Description of the Related Art
A typical gas turbine engine has a substantial number of electrical components which serve, for example, to sense operating parameters of the engine and/or to control actuators which operate devices in the engine. Such devices may, for example, control fuel flow, variable vanes and air bleed valves. The actuators may themselves be electrically powered, although some may be pneumatically or hydraulically powered, but controlled by electrical signals.
Electrical power, and signals to and from the individual electrical components, is commonly transmitted along conductors. Conventionally, such conductors may be in the form of wires and/or cables which are assembled together in a harness. In such a conventional harness, each wire may be surrounded by an insulating sleeve, which may be braided or have a braided cover.
By way of example, FIG. 1 of the accompanying drawings shows a typical gas turbine engine including two conventional wiring harnesses 102, 104, each provided with a respective connector component 106, 108 for connection to circuitry, which may be for example accommodated within the airframe of an aircraft in which the engine is installed.
The harnesses 102, 104 are assembled from individual wires and cables which are held together over at least part of their lengths by suitable sleeving and/or braiding. Individual wires and cables, for example those indicated at 110, emerge from the sleeving or braiding to terminate at plug or socket connector components 112 for cooperation with complementary socket or plug connector components 114 on, or connected to, the respective electrical components.
Each conventional harness 102, 104 comprises a multitude of insulated wires and cables. This makes the conventional harness itself bulky, heavy and difficult to manipulate. The conventional harnesses occupy significant space within a gas turbine engine (for example within the nacelle of a gas turbine engine), and thus may compromise the design of the aircraft, for example the size and/or weight and/or shape of the nacelle.
Conventional harnesses comprise a large number of components, including various individual wires and/or bundles of wires, supporting components (such as brackets or cables) and electrical and/or mechanical connectors. This can make the assembly process complicated (and thus susceptible to errors) and/or time consuming. Disassembly of the conventional harnesses (for example removal of the conventional harnesses from a gas turbine engine during maintenance) may also be complicated and/or time consuming. Thus, in many maintenance (or repair or overhaul) procedures on a gas turbine engine, removal and subsequent refitting of the conventional electrical harness may account for a very significant portion of the operation time and/or account for a significant proportion of the potential assembly errors.
The electrical conductors in the conventional harnesses may be susceptible to mechanical damage. For example, mechanical damage may occur during installation (for example through accidental piercing of the protective sleeves/braiding) and/or during service (for example due to vibration). In order to reduce the likelihood of damage to the conductors in a conventional harness, the protective sleeves/braiding may need to be further reinforced, adding still further weight and reducing the ease with which they can be manipulated. Similarly, the exposed electrical connectors used to connect one conductor to another conductor or conductors to electrical units may be susceptible to damage and/or may add significant weight to the engine.
Gas turbine engines contain oil tanks to provide storage for oil and allow air entrained in the scavenged oil to come out of solution and separate. The tank is conventionally made of metal and is mounted off the engine casings using a series of brackets and rods.
The oil leaves the tank and travels to an oil pump where it is pressurized and then distributed to various parts of the engine where it is used to lubricate the bearing chambers and gearboxes.
After use within the engine, the oil and entrained air is returned by a scavenge pump. An oil/air separator separates the oil from the air. The largely oil-free air is ejected overboard and the oil re-enters the tank.
A fuel-cooled oil-cooler (FCOC) comprising a heat exchanger which cools the oil and heats incoming fuel is generally provided. Without the FCOC, the oil would eventually overheat, degrade and fail to perform. However, it is also know to use air-oil heat exchangers (AOHEs) to cool the oil using fan air.
The way in which the oil system elements are connected together varies from engine to engine. However, the oil tank is expensive and heavy as a part and due to the dedicated mounting features that it requires. The tank also takes up space on the engine, and electrical systems have to attach to it or avoid it, which increases cost and complexity.